But isn't it better than salt? Or being sued by a visitor who slips and breaks something?

I never use anything myself. When we have an Arctic Front I only encounter salt here and there, with lots of walks and other surfaces never being treated. To slip and fall on our walk somebody has to cross miles of other icy surfaces first.

I have seen fertilizer 'disolve' young concrete. I'm not a salt user either. A flat shovel works for me, and the sooner I can get at it before it's packed by foot traffic, the better.
My neighbor used hot water, but it made the walk so slick he had to pour sand on it. The sand was promptly tracked into his house by people and his dogs. His wife was NOT happy.

I don't know if urea will melt the ice or not. I do know it is not the fertilizer of choice in winter. It's going to wash away before the plants can use it for one thing, and urea is strong enough that people do regularly kill their plants by overdose of urea.

Free urea comes out the urethra. My piss stinks.

My neighbor used hot water, but it made the walk so slick he had to pour sand on it.

LOL!! You gotta wonder what some folks are thinking. The logic of using anything that has freeze potential, hot or not at application, escapes me. Did he think the water was magically going to dry up and disappear in subfreezing weather?

Often scraping is not sufficient to remove ice/black ice in very cold weather. My first choice would be sand - no toxicity or pollution issues - but with the availability of a good doormat at hand and/or the removal of outdoor shoes before entering the house. And if you have quality hardwood floors, maybe the potential risks posed by salt or urea would be a better choice :-)

muddydogs, could have gone without that sentiment, especially the last portion. Not sure what value, if any, that added.

It does seem being seen repeatedly urinating on your front walk could serve to reduce the frequency of visitors walking on it during icy conditions.

I think sand is what utilities here use most on our roads.

I use sand or kitty litter(sparingly). Both work well and are easy to clean up when the time comes.

When the temperature is only a few degrees below freezing, calcium nitrate is very effective. It absorbs moisture from the air, works quickly, and is fine on concrete. It's best to get the solution grade rather than the agricultural (coated) grade.

I see this question is several years old, and some answers simply don't address the initial question. I have used a urea product for over 25 years. Available in 50# bags, it was about $40 back then, maybe over $100 now, but I still have enough left from 12 years ago to fill several 1-gallon milk jugs. I keep one jug in car (also a kid-size plastic shovel neither of which I have ever had to use), another jug in garage for ease of application. How much you will use depends on how much concrete you have and how often you get actual ice as compared to snow. It works best if scattered on walks and drive PRIOR to icing up, and maybe several times during. Don't bother using it in snow--you're wasting money. Keep the bag tightly closed, it tends to clump but can be broken up without too much difficulty. It is worth the investment if you are planning to stay in your home for 10 or more years and don't want scaled concrete or the expense of replacing. Otherwise, go for the cheap.